Ver en Cuevana. Mammy features Al Jolson as the star of a travelling minstrel show, appearing in cities and towns across the U.S. Jolson falls in love with an actress in the troupe (Lois Moran), but she loves another (Lowell Sherman). Sherman is shot onstage as part of a comedy bit, and it is assumed that Jolson is guilty of putting the bullet in the gun.